Chop the lettuce and put it in your salad spinner or a large bowl, rinse and drain very well. Pat the lettuce dry (if you have the time you can wrap the lettuce in paper towels and refrigerate briefly to help it crisp up).

Add the lettuce, shallots, and lemon zest to a bowl.

Season with kosher salt, black pepper, lemon juice, and olive oil. Toss to combine.

Add the Parmesan cheese and red pepper flakes (optional) and toss again. Serve.